Exosome microRNA signatures in patients with complex regional pain syndrome undergoing plasma exchange

Enrique Aradillas,Guillermo M Alexander,Seena K Ajit,James E Barrett,Ahmet Sacan,Sabrina R Douglas,Botros B Shenoda,Sujay Ramanathan

doi:10.1186/s12967-019-1833-3

Abstract

BackgroundTherapeutic plasma exchange (PE) or plasmapheresis is an extracorporeal procedure employed to treat immunological disorders. Exosomes, nanosized vesicles of endosomal origin, mediate intercellular communication by transferring cargo proteins and nucleic acids and regulate many pathophysiological processes. Exosomal miRNAs are potential biomarkers due to their stability and dysregulation in diseases including complex regional pain syndrome (CRPS), a chronic pain disorder with persistent inflammation. A previous study showed that a subset of CRPS patients responded to PE.MethodsAs a proof-of-concept, we investigated the PE-induced exosomal miRNA changes in six CRPS patients. Plasma cytokine levels were measured by HPLC and correlated with miRNA expression. Luciferase assay following co-transfection of HEK293 cells with target 3′UTR constructs and miRNA mimics was used to evaluate miRNA mediated gene regulation of target mRNA. Transient transfection of THP-1 cells with miRNA mimics followed by estimation of target gene and protein expression was used to validate the findings.ResultsComparison of miRNAs in exosomes from the serum of three responders and three poor-responders showed that 17 miRNAs differed significantly before and after therapy. Of these, poor responders had lower exosomal hsa-miR-338-5p. We show that miR-338-5p can bind to the interleukin 6 (IL-6) 3′ untranslated region and can regulate IL-6 mRNA and protein levels in vitro. PE resulted in a significant reduction of IL-6 in CRPS patients.ConclusionsWe propose that lower pretreatment levels of miR-338-5p in poor responders are linked to IL-6 levels and inflammation in CRPS. Our data suggests the feasibility of exploring exosomal miRNAs as a strategy in patient stratification for maximizing therapeutic outcome of PE.

Highlights

Therapeutic plasma exchange (PE) or plasmapheresis is an extracorporeal procedure employed to treat immunological disorders
Isolation and characterization of exosomes Exosomes were isolated from the serum obtained from six complex regional pain syndrome (CRPS) patients, grouped retrospectively as three responders and three non-responders both before and after PE (Fig. 1, Table 1)
The exosomes displayed a size below 100 nm under a transmission electron microscope (TEM) (Fig. 2a, b)

Summary

Introduction

Therapeutic plasma exchange (PE) or plasmapheresis is an extracorporeal procedure employed to treat immunological disorders. Exosomal miRNAs are potential biomarkers due to their stability and dysregulation in diseases including complex regional pain syndrome (CRPS), a chronic pain disorder with persistent inflammation. Therapeutic plasmapheresis or plasma exchange (PE) is an extracorporeal blood purification technique designed to remove large-molecular-weight substances [1]. The substance to be removed is sufficiently large (≥ 15 kDa), has a comparatively prolonged half-life so that its removal provides a therapeutically beneficial period of reduced serum concentration, or the rapid removal of acutely toxic substance resistant to conventional therapy is clinically indicated [1]. PE is a widely used therapeutic procedure in many immunologic renal and neurological disorders, enabling the removal of pathogenic antibodies and circulating immune complexes that can cause inflammation. Often used in combination with immunosuppressive therapies, PE has led to a steady increase in survival rates over the last 40 years in these diseases with a poor prognosis without treatment [2].

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